I've adopted a biphasic sleep pattern of sorts by chance. It started by occasionally falling asleep when putting my son to sleep, and when I'd wake up I'd compensate by staying up longer.
After a while I realized it works very well for me to got to sleep for a couple of hours around 8 when he goes to sleep, and then stay up for a few hours before going back to sleep - I usually feel very mellow and relaxed when waking up after my first sleep period, and then very energized after I've been up for a little while. I get far more done this way than by trying to make myself work on stuff at the tail end of a long day. In fact, I'm coming out of my "mellow and relaxed" phase after my first sleep period right now, and is about to start working on a project...
Sometimes I end up "exploiting it" by cutting my total number of hours of sleep drastically, and feel little ill effect as long as I compensate with sufficient rest the following evening.
Occasionally I'll combine this with a 30 minutes nap at lunch time. If not I'll usually spend that time meditating instead.
I did this for the first two years of college-- I'd often sleep for about 3-4 hours each night before class, and then sleep another chunk of time in the afternoon. However, it had the opposite effect on me as it became more and more difficult to go "back" to sleep in the afternoon unless I waited until the evening.
What ended up happening the last year or so is that I started sleeping 5-6 hours per night without a nap, and then sleeping more on the weekends. Surprisingly, this schedule (with morning coffee) got me through classes much better than having a combined total of 8 hours per night.
I started researching sleep to build a sleep tracking app and the theory (there are a number of books regarding this) is that your body can catch up on a certain amount of sleep "debt" within a period of 1-2 weeks. The "debt" is not a scientific measurement but within 14 days, your body has a general idea of how much sleep/rest is missing, and if the debt is made up gradually instead of all at once (and also by going to bed earlier rather than sleeping in), it can actually decrease the effect of drowsiness from past nights.
Actually now that I started working I sleep 7 hours a night and wake up the same time every morning and it's the first time in 6 years I don't need coffee to get through the day.
Disclaimer-- I also referenced a product I built. The app is called SleepBot and it's a very simple mechanism to help people track sleep and get an idea of their sleep "debt" over short periods of time. As David mentioned, sleep has been an untapped market but there's recently been an influx of sleep apps into the market including tackers, sound machines, and alarms. I think what we're seeing is an increased concern for sleep as more of us try to figure out how to improve our health beyond diet and exercise.
> . However, it had the opposite effect on me as it became more and more difficult to go "back" to sleep in the afternoon unless I waited until the evening.
8 here for me is 8pm. So I'll sleep 8pm until somewhere between 10 and 11.30pm depending on how rough the day was, and then get up and stay up anywhere until around 1.30am to 3.30am and go to bed and sleep until 6am.
I don't think I could deal with sleeping in the afternoon - it has to be when it's reasonably dark out, and it definitively helps to have a rough enough schedule and short enough total amount of sleep to be properly tired by the time I go down for the first round.
I rarely sleep more than 6 hour total during the evening/night, but will often catch up with a nap during the day on weekends.
> I also referenced a product I built. The app is called SleepBot and it's a very simple mechanism to help people track sleep and get an idea of their sleep "debt" over short periods of time.
Hey, nice to meet you :). I'm using SleepBot on my phone for over a year now, it's great!
I did this for a year during high school and loved it. That mellow feeling is a very particular state of mind that I really cherish. I've yet to encounter it in any other circumstance. I recall reading on Wikipedia that a number of historic writers are reported to have induced this state of mind for the purpose of writing.
Unfortunately I had to stop because I was keeping my parents awake at night – and now I live in New York and my evenings are always occupied – but I hope that one day when my life calms down I'll be able to return to that schedule.
Strange (and boring... you've been warned) little anecdote.
Yesterday (like so many days, ha) I spent too much time typing out silly posts for HN. Last night, I couldn't sleep well because of some noise outside and I had this dream. One of those dreams where it is so vivid and the story line is so clear, and there are "scenes" almost like a film where the "camera" zooms in on some aspect, that you wake up remembering the details and go "WTF? What does that mean?"
So I thought about some of the things I remebered for a little bit. Some of these details made absolutely no sense. They served no purpose in the storyline of the dream. And suddenly it hit me they were derived from words I had used in HN posts. Not topics, but individual words. My brain had woven them into the story. And it had done so with some pretty crafty storytelling. I'm not sure I could have done it so well if I was awake.
As if you gave someone a list of random words and said, "Make up a story and weave each of these words into the story."
I guess this is nothing unusual. Probably happens to people every night. But it left me thinking about how just how "self-driving" the brain is. What the heck is it doing when we go to sleep? It is running on its own software, to use a computer analogy. And it's not exactly "open source" code. I would love to see how that code works.
"An uninterpreted dream is like an unopened letter."
Dreams often have many layers of meaning. You might want to try keeping a long-term, detailed record of your dreams, and spending some time each day trying to make sense of them and relating them to your life and to other dreams. You might be surprised to find just how rich they are with meaning.
You can read meaning into anything. For the most part though, dreams are just synapses firing randomly. I wouldn't read too much into them, or at least not take the interpretations too seriously.
What's that movie with Eddie Murphy where he's an alien spaceship? It like this team of little people (cells, proteins, DNA, whatever) trying to make sense of all the stupid stuff you, the lumbering gene robot, got up to during the day. All I gave them to work with was a bunch of words on a webpage. Doesn't make for the most interesting or coherent storyline for a dream. One can imagine them saying, "When is this guy going to get off that stupid website and give us some real material to work with?" :)
not entirely randomly, but processing stuff that's been "on your mind" and not packed away in long-term memory.
I imagine it (non-scientifically) as the brain's trash compactor, finishing up all the half-completed thoughts of your day, not necessary in any sort of logical way, like mashing the pieces of a jigsaw puzzle together regardless of how well they fit, to get something that just barely fits together at a glance.
Disclaimer: I'm going to reference a product I built.
The science of sleep is a strange thing. Sleep is ubiquitous (after all, everyone needs to sleep), and almost everyone I know complains of being tired, or constantly groggy, or stressed due to the limited amount of sleep that they get every night. I know this particularly well, because I suffer from mild insomnia that keeps me awake far later than I should be. I try to use this time well, to create projects, or to learn new things, or to read books, but after a certain time in the night, one's brain starts to become mostly useless -- knowledge isn't retained.
All of that is background for an experience I had in late 2010. As usual, I had been sleeping badly -- getting about 4.5 hours of solid sleep per night for several weeks -- and was feeling pretty terrible, as you might imagine. That night, however, and for whatever reason, I slept beautifully for eight hours... but when my alarm clock went off, I felt terrible. I felt worse than I'd felt on four and a half hours' sleep. How was this possible?
It really bothered me, especially because I'd been so happy that I finally slept a "normal" night's sleep. Did I have some other sleep disorder, maybe one that produced insomnia as just a symptom? I researched, and tried to figure out what was really happening. I couldn't stand the grogginess I felt every morning.
During my research, which lasted probably about a month, I realized that something that made a major impact on me was the stage of sleep during which I woke up. Since sleep cycles last about 90 minutes, I felt better waking up between cycles (4.5 hours is about 3 complete cycles) than waking up in the middle of a sleep cycle (8 hours is 5.3 cycles). It turned out that this phenomenon was called "sleep inertia."
For awhile, I'd try to time this myself. I'd take a piece of paper, and count backwards from the time I needed to wake up in between cycles, then add on some time to fall asleep. I started to notice incredibly less grogginess in the morning. My new technique was amazing.
I tried sharing it with some of my friends and colleagues whom I knew also had problems getting up in the morning (who doesn't?), but it turns out that doing even simple math (subtraction) was not an activity people wanted to do right before bed. I'm not a math guy myself, so I couldn't really blame them. The timing happened to work out that I was teaching myself jQuery at the time, so I figured I'd create a little webapp for myself and my friends to use. That's how http://sleepyti.me was born.
In November 2010, when Sleepyti.me first launched, I asked HN and later Reddit's /r/programming for advice related to design and usability -- I am not a web design guy. That helped, but I ended up keeping the minimalist design in place. This choice was partially because I think it looks nice and clean, and partially because I'm not very good at design... at all. Anything more complicated and it probably would have looked terrible, knowing my design skills.
The site, much to my surprise, caught on very quickly. Social networks (Twitter & StumbleUpon, mostly) as well as traditional media found it effective and intriguing. I ended up giving several interviews about the site, being featured in LifeHacker, and being overall far more popular than I'd ever imagined. For example, I received 300,912 visits to the site last week.
I don't allow donations, and I haven't released an official mobile app yet, but the single banner page on the site has done very well for me -- I've earned $1500-$2000 per month since early 2011. It's not a startup by any means, but it's certainly a nice way to bring in some extra income from a side project.
I think the point I'm trying to make is that the article is right: the science of sleep is strange, and at times counter-intuitive... but in my opinion, it's also an untapped market. After all, we all just want a good night's sleep, don't we?
This sounds like a gross oversimplification. For one thing - even if 90 minutes is the average length of a sleep cycle, this surely varies between humans. My sleep cycle might easily be 80 minutes or 100 minutes long, rather than 90. If I were to use sleepyti.me, it might recommend that I go to bed at 11:00pm to get up at 6:30am. But if my sleep cycle is only 80 minutes long, it will be 40 minutes out in its recommendation, which means that I would wake up in the middle of a sleep cycle, rather than at end of one - exactly the opposite of what it's supposed to achieve!
In addition, although the first sleep cycle averages 90 minutes, the second to fourth cycles are generally 100-120 minutes [1] which again throws off your calculations.
In short, I'm extremely sceptical that such a simple rule could ever be effective for most people.
That doesn't mean anything. You need a real study (placebo works great you know). crntaylor is right. The sleep stages differs a lot between individuals. You need to analyze brain waves in order to be more precise (you could also try to detect movements like the "Sleep as android" app on android. But that's far from perfect.)
No, in this case it's actually not. Mathematically. See your parent for proof. And please do not bring the "a billion flies can't be wrong" argument into this.
For me, it has everything to do with consistency. Then my brain adapts and is not in deep sleep when my alarm goes off.
Consistency can be the number of hours asleep or the time I get up, and takes about three days to set in. It gets even better if I break up my sleep into, say, 3 hour chunks; instead of just sleeping for multiples of three hours, I inform my body when it's time to start and stop sleep cycles by waking up for 20 minutes. It is supposedly more efficient because your brain on its own spends longer than necessary in between sleep cycles, which is a waste of time.
If you don't mind the question: what kind of activity do you need to have in a site to generate that kind of revenue from it? ($ 1500 - $ 2000). Is it something in the order of, say, 10k ad views per month, 100k, or something bigger like 1 million, or is any other interesting factor that needs to be considered?
I'm not the OP, but I've been running ad-supported sites since before the dotcom crash of 2000, so hopefully I have some useful insight on this.
As an extremely rough benchmark, assuming $1 - $2 per 1000 page views on most sites is a reasonable baseline. Not all sites will be able to get to this, and some will get to far more, based on monetisation methods, ad placement (VERY important and frequently undervalued), number of ads, and niche served. Generally, the value of the ads increases in direct proportion to the spending power of the audience and the extent to which they arrive on the site intending to spend money. Sites offering investment advice do very well on ad payouts - free Flash game sites, not so much (although they can make it up on volume).
So for $1500 - $2000, you should probably assume you'll need a million page views a month. Some experimentation with ad placement or a higher-value niche will reduce that. I do know of people who are generating at least that much revenue in ads with 100k page views a month, but that's in very specific, high-paying niches.
I use an alarm app called Sleep Cycle, which basically monitors my movement and tries to wake me up at a good time. Similar idea to what you're showing, but a bit more dynamic (which could be good or bad, I suppose). Any thoughts on the two approaches?
For anyone who cares, I recommend Sleep Cycle most highly, or anything that gets you awake at a time more suited to your natural rhythm than an arbitrary alarm clock, whether Mr. Shaw's solution or something else. The difference really is remarkable, just as he says.
Just wanted to say that I use sleepyti.me a few times a week to decide my alarm time. It's really great and the only reason I use it lesser now is because I can just calculate the sleep cycles in my head (yeah programmers/math people aren't your target audience :P). But hey! Thanks for a brilliant tool and an eye opening insight into sleep patterns.
Since sleep cycles last about 90 minutes, I felt better waking up between cycles (4.5 hours is about 3 complete cycles) than waking up in the middle of a sleep cycle (8 hours is 5.3 cycles). It turned out that this phenomenon was called "sleep inertia."
I read this too and while I've not been so good these past three weeks, prior to that I've been sleeping as close to exactly 7.5 hours as possible and for the first time ever, I was able to consistently get up at 6:30 each morning without tiredness or finding it hard to get up. I picked 7.5 hours so that I'd have a good long sleep to take me through busy & stressful days, but on nights when I wasn't able to get to bed by 11pm, I picked a shorter multiple of 90 minutes and it works just as well except that if its too short over all, I start feeling drowsly earlier in the day.
We both love Sleepyti.me and it’s awesome to hear that you’re making some money off of it. (If you’re uncomfortable with us keeping the same name drop one of us an email.)
When you first posted about sleepyti.me here on HN, I was enduring a long phase where I was having a particularly hard time falling asleep at night. I would often lie in bed for two or three hours before I finally drifted off. Compounding the issue was my tendency to constantly measure and analyze how long I'd been trying and how much sleep I would (not) get if I fell asleep "now", always comparing those figures with factoids from articles I'd read about how much sleep we need, sleep cycles, etc. Then I came across this line on sleepyti.me's results page:
"The average adult human takes fourteen minutes to fall asleep, so plan accordingly!"
Now, instead of measuring my sleeplessness by the hour or by the sleep cycle, I started measuring by multiples of fourteen: "Okay, it's only been 28 minutes since I got in bed. That's only two times the average." "Now I'm at ten times the average. This is ridiculous." I started harboring a grudge towards all those "average" people who could fall asleep so quickly. I wondered if I was enough of a statistical outlier to skew the average up to fifteen or even sixteen minutes. I even began to begrudge _you_ for including that seemingly innocent statistic on a website intended to help people sleep better. I had no idea who you were, but I hated you for lodging that figure in my subconscious. These were the racing, irrational thoughts of my addled, sleep-deprived brain.
At the same time, in part because of that bit of trivia on your site, I started realizing that I had a real problem. My lack of sleep was affecting my concentration, my work, my relationships, pointing inevitably towards a long downward spiral that I desperately wanted to avoid. I began to critically examine my sleeping patterns, my sleeping environment, what I did every night and every morning, my diet—my whole life, in fact. Over the course of the next few months, I experimented with every variable I could think of.
I'm proud to say that today, I'm sleeping better than ever. I'm able to fall asleep much more easily, and my overall mood and outlook has improved considerably. It's by no means perfect though—it's very much an ongoing, concerted effort. For those of you enduring a similar struggle for sleep, here are a few of the things that made the biggest difference for me:
- Don't get hung up on numbers. Stop counting the minutes that you're not sleeping. Easier said than done for many of us, I know, but it's huge. Place digital alarm clocks and the like out of sight from your bed, and resist the urge to check the time on your phone.
- If you're on the computer late at night, use f.lux to automatically adjust the color temperature of your screen. The bright light of your LCD screen can mess with your body's natural rhythms, and f.lux helps to counter that. It took me a little while to get used to it, but once I did, I noticed a marked decrease in the "racing mind" syndrome when I used my computer right before bed. Here's the link: http://stereopsis.com/flux/
- Avoid caffeine after lunchtime. (This one will vary widely for different people, but since I'm a caffeine lightweight, it's pretty early in the day. Find your own cutoff.) Also try different caffeinated drinks. For instance, if I drink coffee at any time of the day, I'll likely have trouble sleeping that night, so I drink black tea almost exclusively.
- Don't go to bed on an empty stomach. I can't fall asleep if I'm hungry.
- Read! I started reading in bed every single night about a year and a half ago, and it's my favorite way to shut my brain off at the end of the day. Of course, certain books are better to fall asleep to—the best ones will keep you interested without being so engaging that you can't put it down. (I made the mistake of starting the Hunger Games at about 1:00am a couple of weeks ago, and I ended up reading the entire thing that night. I only got two hours of sleep before work the next morning.) Find what works for you.
- If I'm still having trouble falling asleep after reading, I will often "replay" the last couple chapters of whatever I read in reverse. See if you can remember everything that just happened and work your way back to where you started that night. I read about this trick somewhere on the web (amongst a bunch of other tips that didn't help), and it seems to work wonders for me. If you don't read at night, try recounting your day (even the boring stuff) backwards instead.
- Don't beat yourself up if you still struggle to sleep. It's okay, and it _will_ get better. (On that note, please consider seeing a doctor if your sleeplessness persists!)
Finally, to David: Thank you for building sleepyti.me. It serves a simple but significant purpose, and it does so elegantly. And while it fed my irrational, sleep-deprived hatred of non-insomniacs for a little while, it also became a catalyst for real change in my life.
This is just personal experience, but I have a hunch that a lot of sleeplessness is also caused by weird schedules. In the weektime you get up at 6, you go out on Friday and sleep until noon, and then on Sunday get up by 10, and then back to 6 AM again on Monday. In high school and college, it used to take me about an hour to get to sleep, and I'd always wake up tired after hitting the snooze button for three, four times.
Since about half a year ago, I've been getting up every day at 6 (week or weekend and in the first weeks of trying this out, whether you're tired or not) and all my sleeping problems have disappeared. To make sure I don't think about it, I hit the shower first and then decide whether I want to go back to bed... which at that point, you never do. Not tired. Easy to fall asleep. Don't need caffeine in the morning to stay awake.
I know there's more to insomnia than just bad habits and I don't want to be the kind of guy who argues that sleep problems are "just inside of your head", but I do wonder whether the fact that sleep issues are so pervasive in our society might have to do with a lack of routine in most people's lives.
Don't go to bed on an empty stomach. I can't fall asleep if I'm hungry.
This is hugely bad advice. Consistently going to bed with anything other than an empty stomach can lead to acid reflux (GERD). This is especially so after having chocolate before bed time, since chocolate loosens the muscle between your stomach and esophagus and allows acid to enter the tender areas of your esophagus, causing scaring and pain.
I have severe issues with this because of years of laying down after eating dinner. The muscle referred to above, in my case, is permanently damaged, such that it won't close all the way. I have to be very careful what I do after eating. It will be this way for the rest of my life and it's a complete pain in the ass.
Not everyone experiences this, but many will. I strongly recommend people do not follow the parent comment's advice.
Thanks for the warning, but isn't consistently going to bed with a full stomach different from going to bed with a light snack every once in a while to make sure your stomach is not growling?
Yes, it is, but only if that snack doesn't include chocolate or peppermint or one of the other foods that enables reflux. Ibuprofen (as well as all the NSAIDs) do, too. If you are on any medication, check the info on it to see if it promotes reflux.
One thing I want to emphasize here is f.lux. It works. In fact it works brilliantly – it has had a profound effect on my sleep quality of the last year.
I personally have found that f.lux is insufficient. It does significantly tone down the amount of blue that my laptop screen puts out, but even when set to the most red-shifted setting possible, my laptop screen still puts out enough blue light to keep me from getting sleepy.
"without being so engaging that you can't put it down"
I find re-reading (good, entertaining, no too serious) novels that I have already read before, works best. Since you have already read the thing previously, it's easier to put it down in the middle.
dfc@ronin:~$ apt-cache search redshift
gtk-redshift - Adjusts the color temperature of your screen with GTK+ integration
redshift - Adjusts the color temperature of your screen
Side note about f.lux. I installed f.lux on my windows XP laptop and it kind of messed up the settings. The funny thing is even after uninstalling f.lux, my laptop retained the brightness settings that were set by f.lux. (Thankfully, it is fixed now.) It also crashed a few times due to its memory consumption.
I use sleepyti.me quite often and it's helped me a lot. I remember about a year ago I found that sleeping ~6.5 hours or 9.5 hours felt way better than 7-8, but I never looked into why that was. After discovering your app, I now know why and how to combat all-day grogginess. So thank you.
If I get really involved in something and realise it's past my normal bed time, I'll check sleepyti.me and if it's close to a good time to fall asleep I'll take some melatonin and fall asleep, otherwise I think to myself "I'll have to survive on one less cycle tonight." and keep working.
By the way, in your research did you learn where the 8-hour myth originated?
Re http://sleepyti.me: One small issue is that sleep schedule is calculated after setting the hour and minutes, but before getting a chance to set the AM/PM.
Sleep still seems incredibly mis-understood relative to other essentials in life - like nutrition. If i think about the events in my life that wrecked sleep they were 1) kids 2) stress at work 3) chronic illness 4) family anxiety and they all occurred or accelerated in the back half of life. I imagine this will impact my long term health as much as nutrition. Yet few have effectively studied it like they have eating habits.
I'm extremely pissed I went the first 27 years of my life without knowing this. It completely changed my life.
When you wake up you are dehydrated. Immediately have a sip of pickle brine and a cup of water. The electrolytes (salt and potassium) help you absorb the water quickly. You will feel MUCH better. Coconut juice is another possibility if you find pickles gross.
Anecdotally, adopting this pattern of sleep has helped with my workaholism and overall satisfaction. Before I was going to sleep somewhere in the range of 1:30am - 4:30am, depending on when I finished a project, and woke up between 9am - 10am. Now, I take a nap on most days, fall asleep around 11, wake up around 2:30am and do a little thinking and/or reading or most useful: note-taking. Then, I go back to sleep and wake up with the sunrise. It's really done wonders for how I feel during the day. It may not be for everyone, but it works for me, but I also have a work environment that is supportive of naps which makes it a lot easier.
I currently have a sleep schedule similar to your previous schedule... work until I'm done with projects, usually Midnight to 2:00 am, sleep until 9 or 10 am. However I've noticed recently that I wake up nearly every night around 5 am, regardless of when I go to bed, and then I lay in bed irritated that I can't get back to sleep until around 7:30 am, then I doze off and wake up again around 10 am. So based upon your comments, and the article, I'll try getting up when I wake around 5 am and doing something productive, and then go back to bed around 7:30 am and get a few more hours of sleep. I don't know why, but I would have never considered doing that, I guess because I'm always irritated that I can't sleep in the middle of the night. My work environment would allow me to nap during the day, but I find it uncomfortable to sleep during the day.
I read an interesting book a few years ago written by a guy exploring the different states our brain goes through during a twenty-four period; this included experimenting with polyphasic sleep. He spends (IIRC) a month living in a cabin in the wilderness, sleeping according to the rising and setting of the sun; after a week or so his body reset itself to a two-phase sleep cycle as described in the nytimes piece.
I get up at least 3-4 times each night, I'm assuming in between my sleep cycles. I'm completely awake for a few minutes before falling back to sleep.
I don't have any problems during the day and don't feel tired. I always thought we needed 8 continuous hours, but some research I've read says it's okay to actually get up in between, as long as you get 8 hours total.
If companies, especially tech firms and startups, have become much more conscious and amenable to the need to allow their employees to work out, perhaps they can also start allowing a naptime break of twenty to forty minutes. It doesn't have to be "just a crazy Google benefit."
So if you're used to sleeping for eight hours at a time...should you set your alarm for four hours, wake up, do something sedate for a while, and then go back to bed? Should it be more like 4.5 so that (in theory) it happens at the end of a 1.5-hour sleep cycle?
I don't think you should set an alarm ever if you can help it.
If the theory is that bi-phasic sleep is ideal and natural for us, you should fall into that pattern naturally. All you need to do is go to sleep around the time that the sun goes down. It's just that "easy".
> Employees at Google, for instance, are offered the chance to nap at work because the company believes it may increase productivity.
What percentage of employee-days at Google actually involve a nap? 1%? 0.01%? Is it any higher than the traditional comic practice of "curl up under your desk"?
> What percentage of employee-days at Google actually involve a nap? 1%? 0.01%? Is it any higher than the traditional comic practice of "curl up under your desk"?
Complete anecdata but: I've seen people curled up on couches in the middle of the day plenty of times. I think the point is that, at Google, you won't be frowned upon for this. (Whereas it may be much more likely at other companies.) Not that you're mandated to nap after lunch or anything.
I've heard of a few strategies around sleep... one is 'amount', one is 'waking', and one is 'quality'. Things like sleep apnea effect the quality, the http://sleepyti.me site helps with waking, and I'm still curious about the amount.
After a while I realized it works very well for me to got to sleep for a couple of hours around 8 when he goes to sleep, and then stay up for a few hours before going back to sleep - I usually feel very mellow and relaxed when waking up after my first sleep period, and then very energized after I've been up for a little while. I get far more done this way than by trying to make myself work on stuff at the tail end of a long day. In fact, I'm coming out of my "mellow and relaxed" phase after my first sleep period right now, and is about to start working on a project...
Sometimes I end up "exploiting it" by cutting my total number of hours of sleep drastically, and feel little ill effect as long as I compensate with sufficient rest the following evening.
Occasionally I'll combine this with a 30 minutes nap at lunch time. If not I'll usually spend that time meditating instead.